1. Field of the Invention
The present invention relates to a technology field of liquid crystal display, and more particularly to a backlight module and a liquid crystal display.
2. Description of the Prior Art
With the development of the liquid crystal display technology, the demand for the function of the liquid crystal display becomes more and more high.
FIG. 1 is a partial structural schematic view of a backlight module of the prior art, which includes a light source 11, a light guide plate 12 and a back plate 13. The light source 11 may be a light emitting diode (LED) for emitting light. The light emitted by the light source 11 can enter into the light guide plate 12. The light-coupling efficiency between the light source 11 and the light guide plate 12 directly influences the light use efficiency of the whole backlight module.
In the prior art, the light guide plate 12 is made of the macromolecule material, such as Polymethyl Methacrylate (PMMA), Polycarbonate (PC) and so on. These materials can expand when being heated. Because the light source 11 can generate a quantity of heat when working and the light guide plate 12 is close to the light source 11, the heat is easy to be transmitted unto the light guide plate 12. As a result, the light guide plate 12 will expand. Accordingly, there must form an enough expanding space between the light source 11 and the light guide plate 12, so that providing the enough expanding space for the light guide plate 12.
Please refer to FIGS. 2A and 2B, which respectively show different gaps D1, D2 between the light source 11 and the light guide plate 12 and schematically show different light-leaking proportions of the light source 11. In FIGS. 2A and 2B, the gap D1 is greater than the gap D2. When the gap is D1, the range of the incidence angle of the light emitted by the light source 11 entering into the light guide plate 12 is smaller so that resulting in a greater light-leaking range therefore the light-leaking proportion is greater. When the gap is D2, the range of the incidence angle of the light emitted by the light source 11 entering into the light guide plate 12 is greater so that resulting in a smaller light-leaking range, therefore the light-leaking proportion is smaller. Obviously, because there exists the expanding gap between the light source 11 and the light guide plate 12 and whether the size of the gap is small or greater, the partial light of the light source 11 can be leaked and cannot enter into the light guide plate 12 so that resulting in a low light entry efficiency and reducing the light use efficiency of the backlight module.
For enhancing the light use efficiency of the backlight module, the expanding gap between the light source 11 and the light guide plate 12 needs to be eliminated. Namely, the light source 11 directly contacts the light guide plate 12. But this will result in there being no the expanding space provided for the light guide plate 12. Once the light guide plate 12 expands to some extent, the light guide plate 12 will be bent and deformed or even be cracked so that lowering the image displaying quality of the liquid crystal display.